Reproducer for talking machines



Patented `luly 22, 1924i.

STUART BERTRAIVL BOOTY, 0F DULW'ICH HILL, NEAR SYEDNEY, NEW SOUTH WALESV.

AUSTRALA. l'

REPRODUCEB FOR T Application filed .Tune 7,

To all whom t may concern.'

Beit known that I, STUART BERTRAM Boo'rr, subjectof the King of Great Britain and Ireland, residing at 33 Barnesbury Grove, Dulwich Hill, near Sydney, New South Wales, Australia, have invented certain new and useful Improvements in Reproducers for Talking Machines, of which the following is a specification.

This invention relates t0 sound-reproducers for talking machines which are operated with either disc records or cylindrical records.

The reproducer needle is set in a socket in a platform the ends of which rest on two cone points which are set far apart on the sound box casing sothat the platform will be freely movable in the direction of the normal oscilla-tion of the needle and stylus; said platform carries a transversely disposed leaf spring, the ends of which extend laterally of the length of the platform at either side of it and are constrained towards the sound box casing so as to hold one end of the platform down on the cone point below it, by means of adjusting screws having cork cushion washers under their heads. A soft mica diaphragm is fitted in the sound box, and a stylus bar, the butt of which is fixed 'in the platform is attached at its operative end to the centre of the diaphragm. The novel feature in the invention is the fitting of a long leaf spring transversely across the platform, with its ends extended atfeither side of it and sepa rately adjustable for tension by means of cushioned screws.

On the accompanying drawings Figs. 1, 2 and 3 are detailed views of a reproducer according to my invention, respectively in side elevation, bottom plan, and end elevation, arranged for operation with records having laterally corrugated grooves.

The reproducer comprises a fiat cylindrical casing 10 fitted with a bezel ring 11 arranged for compressing the packing rings 12-12 fabout either edge of the soft mica diaphragm 13. The neck 14 of this box is adapted to be set on the fore end of the tone arm in the usual way. The lower part of the reproducer body is flattened as shown at 16, and two cone points 17 at the extreme ends of the flat are provided to form resting points for the platform 18. The platform is retained resting on the points 17 ALKING lllACHINES. l

1922. Scrlal No. 566,462.

by a helical spring washer 19 located under the head of a screw 20, which is driven'into a tapped hole in the body of the reproducer. The needle socket 21 is centrally disposed on the platform 18 about midway between the cone points 17. 23 is a binding screw for fixing the reproducer needle 2a in the socket 21. 25 is the stylus arm, which. as usual, is connected to the centre of the diaphragm 13. rfhe end of the platform 18 distant from the holding screw 20ris slotted horizontally and a tensioning leaf spring 2G set in the slot and sweated therein to form a T-head across the platform. It is important that the attachment of this spring to the platform shall be extremely solid and that it shall not depend upon mere screw or rivet fastenings in which local vibration might occur.

rThe leaf spring 26 is of considerable length, being nearly the total length of the platform. rlhe length of the platform is about half the diameter of the diaphragm. The leaf spring 26 is secured back to lugs 28-28 formed on the reproducer casing by means of tensioning screws 29-29 passed through holes in the ends thereof; these screws'are set by means of back nuts 30-30. Under the screw heads 29 cork compression washers 31 are inserted. vWhen the screws 29 are driven home these washers are compressed, they serve the purpose of preventing rattling of the spring 26 against the screw heads 29. rllhe screws 29 are set to establish transverse tension through the spring on the needle and stylus mounting to stress the diaphragm inward and outward or to set it neutral i. e. without ten sion in either direction, the reproducer being set according to the usual practice so that the needle subjected to vibration imposed by the grooves in the record, whether the grooves be of the lateral type or of the hill-and-dale type. The provision of a variable damper for the diaphragm which is controllable so that the diaphragm may be left free to vibrate or may be constrained fthe platform Vin the direction ofv its length minimizes transmission through the needle and stylus bar in a direction parallel to the face of the diahragm. The platform is, however, 'perfectly free for vibratory movement transvers'ely of its length upon its cone point supporters, and its `liberty to vibrate transversely and consequentlythe liberty of the diaphragm to vibrate is controllable by the adjustment of the tensioning screws 29.

The leaf spring 26 is preferably of phosphor bronze about 30 B. W. gauge in thickness, and when used with a diaphragm of about 2 -inoh diameter and proportioned thereto approximately according to the measurements deducible from the drawings, it procures a tensioning of the platform transversely toits length which is variable within extreme limits to accommodate it to the characteristics o-f particular records to secure satisfactory reproduction. It is how- .of vibrations Y ever necessary that the reproducer diarphragm be con'structedof soft vmica. The

`and casing, yielding means for hold-ing one end of sai-d platform `against one of said bearing members, a spring extendingV transversely of and in contact with the other end l of said platform for holding it against the other bearing member, and meansfor adj'ustably supporting the ends of said spring on said casing` In `testimony whereof I affix my signature.

STUART BERTRAM BOOTY. 

